下面程序用异或 *** 作对文件进行加密和解密
/******************设计思路******************/
//根据用户输入的加密/机密密码,
//每次都拿原文件和密码等长度的一个字符串和密码
//对应元素异或进行加密/解密
//另外因为是用异或方法,所以加密和解密就是同一个程序
//即按照同样的加密即是对文件的解密
#include
#include
#include
#include
#include
charfilename[256]//原文件
charpassword[256]//加密/解密密码
constcharfilenametemp[]="temp15435255435325432543.temp"//加密/解密中间文件
voidinputpass(char*pass)//密码输入以"******"显示
voidmain(){
FILE*fp//加密/解密的文件
FILE*fptemp//加密/解密过程临时文件
intpwdlen//密码长度
inti=0//计数器
charch=0//读入的字符
printf("请输入要加密/解密的文件名(全路径名):\n")
gets(filename)
if((fp=fopen(filename,"rb"))==NULL){
printf("找不到文件%s\n",filename)
exit(1)
}//if
printf("请输入要加密/解密的密码:\n")
inputpass(password)
pwdlen=strlen(password)
if(pwdlen==0){
printf("密码不能为空,加密/解密失败\n")
exit(1)
}//if
fptemp=fopen(filenametemp,"wb")//打开中间文件
while(1){
ch=fgetc(fp)//从原文件读入一个字符
if(feof(fp)){//已经读到文件尾
break//退出循环
}
ch^=password[i++]//对原字符和密码进行异或 *** 作
fputc(ch,fptemp)//将异或结果写入中间文件
if(i==pwdlen){//使得原文件每和密码长度相同的固定长度异或加密
i=0
}
}//while
fclose(fp)//关闭打开原文件
fclose(fptemp)//关闭打开中间文件
remove(filename)//删除原文件
rename(filenametemp,filename)//将中间文件重命名为原文件
printf("加密/解密成功\n")//至此加密/解密成功
}
//密码输入以"******"显示
voidinputpass(char*pass){
inti=0
charc
while(isprint(c=getch())){
pass[i++]=c
//printf("*")
}
pass[i]='\0'
printf("\n")
}
#include <stdio.h>#include <string.h>
#include "global.h"
#include "md5.h"
#define S11 7
#define S12 12
#define S13 17
#define S14 22
#define S21 5
#define S22 9
#define S23 14
#define S24 20
#define S31 4
#define S32 11
#define S33 16
#define S34 23
#define S41 6
#define S42 10
#define S43 15
#define S44 21
static void MD5Transform PROTO_LIST ((UINT4 [4], unsigned char
[64]))
static void Encode PROTO_LIST
((unsigned char *, UINT4 *, unsigned int))
static void Decode PROTO_LIST
((UINT4 *, unsigned char *, unsigned int))
static void MD5_memcpy PROTO_LIST ((POINTER, POINTER, unsigned
int))
static void MD5_memset PROTO_LIST ((POINTER, int, unsigned int))
static unsigned char PADDING[64] = {
0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
}
#define F(x, y, z) (((x) &(y)) | ((~x) &(z)))
#define G(x, y, z) (((x) &(z)) | ((y) &(~z)))
#define H(x, y, z) ((x) ^ (y) ^ (z))
#define I(x, y, z) ((y) ^ ((x) | (~z)))
#define ROTATE_LEFT(x, n) (((x) <<(n)) | ((x) >>(32-(n))))
#define FF(a, b, c, d, x, s, ac) { (a) += F ((b), (c), (d)) + (x) + (UINT4)(ac)(a) = ROTATE_LEFT ((a), (s))(a) += (b)}
#define GG(a, b, c, d, x, s, ac) { \
(a) += G ((b), (c), (d)) + (x) + (UINT4)(ac)\
(a) = ROTATE_LEFT ((a), (s))\
(a) += (b)\
}
#define HH(a, b, c, d, x, s, ac) { \
(a) += H ((b), (c), (d)) + (x) + (UINT4)(ac)\
(a) = ROTATE_LEFT ((a), (s))\
(a) += (b)\
}
#define II(a, b, c, d, x, s, ac) { \
(a) += I ((b), (c), (d)) + (x) + (UINT4)(ac)\
(a) = ROTATE_LEFT ((a), (s))\
(a) += (b)\
}
void MD5Init (context)
MD5_CTX *context
{
context->count[0] = context->count[1] = 0
context->state[0] = 0x67452301
context->state[1] = 0xefcdab89
context->state[2] = 0x98badcfe
context->state[3] = 0x10325476
}
void MD5Update (context, input, inputLen)
MD5_CTX *context
unsigned char *input
unsigned int inputLen
{
unsigned int i, index, partLen
index = (unsigned int)((context->count[0] >>3) &0x3F)
if ((context->count[0] += ((UINT4)inputLen <<3))<((UINT4)inputLen <<3))
context->count[1]++
context->count[1] += ((UINT4)inputLen >>29)
partLen = 64 - index
if (inputLen >= partLen)
{
MD5_memcpy((POINTER)&context->buffer[index], (POINTER)input, partLen)
MD5Transform (context->state, context->buffer)
for (i = partLeni + 63 <inputLeni += 64)
MD5Transform (context->state, &input[i])
index = 0
}
else
i = 0
MD5_memcpy((POINTER)&context->buffer[index], (POINTER)&input[i],inputLen-i)
}
void MD5Final (digest, context)
unsigned char digest[16]
MD5_CTX *context
{
unsigned char bits[8]
unsigned int index, padLen
Encode (bits, context->count, 8)
index = (unsigned int)((context->count[0] >>3) &0x3f)
padLen = (index <56) ? (56 - index) : (120 - index)
MD5Update (context, PADDING, padLen)
MD5Update (context, bits, 8)
Encode (digest, context->state, 16)
MD5_memset ((POINTER)context, 0, sizeof (*context))
}
static void MD5Transform (UINT4 state[4], unsigned char block[64])
{
UINT4 a = state[0], b = state[1], c = state[2], d = state[3], x[16]
Decode (x, block, 64)
FF (a, b, c, d, x[ 0], S11, 0xd76aa478)/* 1 */
FF (d, a, b, c, x[ 1], S12, 0xe8c7b756)/* 2 */
FF (c, d, a, b, x[ 2], S13, 0x242070db)/* 3 */
FF (b, c, d, a, x[ 3], S14, 0xc1bdceee)/* 4 */
FF (a, b, c, d, x[ 4], S11, 0xf57c0faf)/* 5 */
FF (d, a, b, c, x[ 5], S12, 0x4787c62a)/* 6 */
FF (c, d, a, b, x[ 6], S13, 0xa8304613)/* 7 */
FF (b, c, d, a, x[ 7], S14, 0xfd469501)/* 8 */
FF (a, b, c, d, x[ 8], S11, 0x698098d8)/* 9 */
FF (d, a, b, c, x[ 9], S12, 0x8b44f7af)/* 10 */
FF (c, d, a, b, x[10], S13, 0xffff5bb1)/* 11 */
FF (b, c, d, a, x[11], S14, 0x895cd7be)/* 12 */
FF (a, b, c, d, x[12], S11, 0x6b901122)/* 13 */
FF (d, a, b, c, x[13], S12, 0xfd987193)/* 14 */
FF (c, d, a, b, x[14], S13, 0xa679438e)/* 15 */
FF (b, c, d, a, x[15], S14, 0x49b40821)/* 16 */
/* Round 2 */
GG (a, b, c, d, x[ 1], S21, 0xf61e2562)/* 17 */
GG (d, a, b, c, x[ 6], S22, 0xc040b340)/* 18 */
GG (c, d, a, b, x[11], S23, 0x265e5a51)/* 19 */
GG (b, c, d, a, x[ 0], S24, 0xe9b6c7aa)/* 20 */
GG (a, b, c, d, x[ 5], S21, 0xd62f105d)/* 21 */
GG (d, a, b, c, x[10], S22, 0x2441453)/* 22 */
GG (c, d, a, b, x[15], S23, 0xd8a1e681)/* 23 */
GG (b, c, d, a, x[ 4], S24, 0xe7d3fbc8)/* 24 */
GG (a, b, c, d, x[ 9], S21, 0x21e1cde6)/* 25 */
GG (d, a, b, c, x[14], S22, 0xc33707d6)/* 26 */
GG (c, d, a, b, x[ 3], S23, 0xf4d50d87)/* 27 */
GG (b, c, d, a, x[ 8], S24, 0x455a14ed)/* 28 */
GG (a, b, c, d, x[13], S21, 0xa9e3e905)/* 29 */
GG (d, a, b, c, x[ 2], S22, 0xfcefa3f8)/* 30 */
GG (c, d, a, b, x[ 7], S23, 0x676f02d9)/* 31 */
GG (b, c, d, a, x[12], S24, 0x8d2a4c8a)/* 32 */
/* Round 3 */
HH (a, b, c, d, x[ 5], S31, 0xfffa3942)/* 33 */
HH (d, a, b, c, x[ 8], S32, 0x8771f681)/* 34 */
HH (c, d, a, b, x[11], S33, 0x6d9d6122)/* 35 */
HH (b, c, d, a, x[14], S34, 0xfde5380c)/* 36 */
HH (a, b, c, d, x[ 1], S31, 0xa4beea44)/* 37 */
HH (d, a, b, c, x[ 4], S32, 0x4bdecfa9)/* 38 */
HH (c, d, a, b, x[ 7], S33, 0xf6bb4b60)/* 39 */
HH (b, c, d, a, x[10], S34, 0xbebfbc70)/* 40 */
HH (a, b, c, d, x[13], S31, 0x289b7ec6)/* 41 */
HH (d, a, b, c, x[ 0], S32, 0xeaa127fa)/* 42 */
HH (c, d, a, b, x[ 3], S33, 0xd4ef3085)/* 43 */
HH (b, c, d, a, x[ 6], S34, 0x4881d05)/* 44 */
HH (a, b, c, d, x[ 9], S31, 0xd9d4d039)/* 45 */
HH (d, a, b, c, x[12], S32, 0xe6db99e5)/* 46 */
HH (c, d, a, b, x[15], S33, 0x1fa27cf8)/* 47 */
HH (b, c, d, a, x[ 2], S34, 0xc4ac5665)/* 48 */
/* Round 4 */
II (a, b, c, d, x[ 0], S41, 0xf4292244)/* 49 */
II (d, a, b, c, x[ 7], S42, 0x432aff97)/* 50 */
II (c, d, a, b, x[14], S43, 0xab9423a7)/* 51 */
II (b, c, d, a, x[ 5], S44, 0xfc93a039)/* 52 */
II (a, b, c, d, x[12], S41, 0x655b59c3)/* 53 */
II (d, a, b, c, x[ 3], S42, 0x8f0ccc92)/* 54 */
II (c, d, a, b, x[10], S43, 0xffeff47d)/* 55 */
II (b, c, d, a, x[ 1], S44, 0x85845dd1)/* 56 */
II (a, b, c, d, x[ 8], S41, 0x6fa87e4f)/* 57 */
II (d, a, b, c, x[15], S42, 0xfe2ce6e0)/* 58 */
II (c, d, a, b, x[ 6], S43, 0xa3014314)/* 59 */
II (b, c, d, a, x[13], S44, 0x4e0811a1)/* 60 */
II (a, b, c, d, x[ 4], S41, 0xf7537e82)/* 61 */
II (d, a, b, c, x[11], S42, 0xbd3af235)/* 62 */
II (c, d, a, b, x[ 2], S43, 0x2ad7d2bb)/* 63 */
II (b, c, d, a, x[ 9], S44, 0xeb86d391)/* 64 */
state[0] += a
state[1] += b
state[2] += c
state[3] += d
MD5_memset ((POINTER)x, 0, sizeof (x))
}
static void Encode (output, input, len)
unsigned char *output
UINT4 *input
unsigned int len
{
unsigned int i, j
for (i = 0, j = 0j <leni++, j += 4)
{
output[j] = (unsigned char)(input[i] &0xff)
output[j+1] = (unsigned char)((input[i] >>8) &0xff)
output[j+2] = (unsigned char)((input[i] >>16) &0xff)
output[j+3] = (unsigned char)((input[i] >>24) &0xff)
}
}
static void Decode (output, input, len)
UINT4 *output
unsigned char *input
unsigned int len
{
unsigned int i, j
for (i = 0, j = 0j <leni++, j += 4)
output[i] = ((UINT4)input[j]) | (((UINT4)input[j+1]) <<8) |(((UINT4)input[j+2]) <<16) | (((UINT4)input[j+3]) <<24)
}
static void MD5_memcpy (output, input, len)
POINTER output
POINTER input
unsigned int len
{
unsigned int i
for (i = 0i <leni++)
output[i] = input[i]
}
static void MD5_memset (output, value, len)
POINTER output
int value
unsigned int len
{
unsigned int i
for (i = 0i <leni++)
((char *)output)[i] = (char)value
}
#ifndef MD
#define MD 5
#endif
#define TEST_BLOCK_LEN 1000
#define TEST_BLOCK_COUNT 1000
static void MDString PROTO_LIST ((char *))
static void MDPrint PROTO_LIST ((unsigned char [16]))
#define MD_CTX MD5_CTX
#define MDInit MD5Init
#define MDUpdate MD5Update
#define MDFinal MD5Final
int main (int argc, char *argv[])
{
int i
if (argc >1)
{ MDString(argv[1])
return (0)
}
}
static void MDString (char *string)
{
MD_CTX context
unsigned char digest[16]
unsigned int len = strlen (string)
MDInit (&context)
MDUpdate (&context, string, len)
MDFinal (digest, &context)
printf ("MD%d (\"%s\") = ", MD, string)
MDPrint (digest)
printf ("\n")
}
static void MDPrint (unsigned char digest[16])
{
unsigned int i
for (i = 0i <16i++)
printf ("%02x", digest[i])
}
C语言设计一个简单的加密解密程序如下:加密程序代码:
#include<stdio.h>
main()
{
char
c,filename[20]
FILE
*fp1,*fp2
printf("请输入待加密的文件名:\n")
scanf("%s",filename)
fp1=fopen(filename,"r")
fp2=fopen("miwen.txt","w")
do
{
c=fgetc(fp1)
if(c>=32&&c<=126)
{
c=c-32
c=126-c
}
if(c!=-1)
fprintf(fp2,"%c",c)
}
while(c!=-1)
}
解密程序代码:
#include<stdio.h>
#include<string.h>
main()
{
char
c,filename[20]
char
yanzhengma[20]
FILE
*fp1,*fp2
printf("请输入待解密文件名:\n")
scanf("%s",filename)
printf("请输入验证码:\n")
scanf("%s",yanzhengma)
if(strcmp(yanzhengma,"shan")==0)
{
fp1=fopen(filename,"r")
fp2=fopen("yuanwen.txt","w")
do
{
c=fgetc(fp1)
if(c>=32&&c<=126)
{
c=126-c
c=32+c
}
if(c!=-1)
fprintf(fp2,"%c",c)
}
while(c!=-1)
}
else
{
printf("验证码错误!请重新输入:\n")
scanf("%s",filename)
}
}
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